If your iPod Nano isn’t showing up in iTunes, disconnect it and set it aside until you update iTunes to the latest version. When iTunes has finished updating, clear your computers temp files and restart your computer. While your computer is restarting, restart your iPod Nano as well.
When your computer and iPod Nano have restarted, open iTunes and connect your iPod Nano. Then click on the iPod box at the top right of the iTunes screen, next to the iTunes store. This will take you to a summary page where you will see an image of an iPod Nano. Click on “Music” next to that tab and then click on “Sync Music”. This will start the syncing process right away and should also make sure your iPod Nano connects to iTunes.